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Size-Distribution of Irradiation-Induced Dislocation-Loops in Materials Used in the Nuclear Industry
No full textNeutron or proton irradiation induced dislocation loops in Zr and its alloys are usually characterized by electron microscopy methods. In plastically deformed materials X-ray line profile analysis (XLPA) is now a well-established tool to determine dislocation densities (DDs) with excellent agreement between XLPA and TEM analysis. In irradiated zirconium alloys, however, XLPA determined DDs are often considerably larger than those obtained by TEM. In ion irradiated Cu and W it was shown that X-ray diffraction or MD simulations give significantly larger dislocation loop densities than conventional TEM analysis, which suggests that the smallest loops remain undetected by TEM. Based on these results we developed a new methodology to determine power-law size-distributions of irradiation-induced dislocation loops. We assume that only loops larger than a certain threshold are fully counted in TEM micrographs, whereas XLPA detects all the loops in the entire size range. This new analysis procedure shows that in neutron irradiated Zircaloy-2 in the channel-box materials the total DD is larger than in the cladding materials, even though TEM counting shows the opposite. We also found that there is a correlation between the reciprocal square-root of <a>-loop DDs and the diameter of <a>-loops. Our work shows that irradiation induced loop-formation and irradiation-damage in general can be better determined when we combine TEM investigations with XLPA
Enhanced process for energy efficient extraction of 1,3-butadiene from a crude C4 cut
No full text1,3-butadiene is an essential platform chemical for producing rubberlike polymers, which is extracted from C4 hydrocarbons that are produced through steam cracking. The current state of-the-art technology is the BASF process that uses thermally coupled extractive distillation (ED) followed by two distillation columns. However, the process requires high temperature heat input, thus high cost hot utility and reduces the possibility for process heat integration. To solve these issues, this study proposes novel enhancements: the ED part is modified with intermediate heating and the classic columns are replaced with a heat pump assisted dividing wall column (DWC). Rigorous simulations were carried out in Aspen Plus for a typical ED process. The intermediate reboiler system is designed to maximize the possible process heat recovery. The results show that the heat pump assisted DWC is able to reduce the energy intensity of the classic distillation section of the BASF process by 54.8% and reduces the total annual costs by 29.9%. Additionally, the intermediate reboiler reduces the energy intensity of the ED section by 8.3% while also reducing the CAPEX of the system due to the need for a smaller recycle compressor. In combination, these modifications are able to achieve up to a 21% reduction in the energy intensity of the overall process, with a payback time of 1 year
Effect of stress and surface finish on Pb-caustic SCC of Alloy 690TT
No full textThe effect of surface preparation on lead-induced stress corrosion cracking (PbSCC) of Alloy 690TT in Pb-caustic solution was investigated using C-rings manufactured from tubing that was either as-manufactured or polished. The surface deformed layer on the as-manufactured samples promoted the formation of an oxide, which reduced the number of sites for crack nucleation. Conversely, the polished surface developed crystallographic corrosion slots from which some of the cracks seemed to initiate. Advanced microstructural characterization complemented with stress analysis of the samples, suggested that the early stages of PbSCC are consistent with a film-rupture/slip-dissolution mechanism and influenced by de-alloying
The effect of quench rate on the β-a″ martensitic transformation in Ti-Nb alloys
No full textWhile Ti-Nb binary alloys have been extensively studied over the years, there are discrepancies in the literature relating to the β-a″ martensitic transformation that indicate an incomplete understanding. In particular, there are inconsistencies regarding the phase constitution of asquenched material and the ability for a″ phase to be thermally-induced. To resolve these issues, the β-a″ phase transformation is studied in a Ti-24Nb (at.%) alloy subjected to two different water quench conditions. It is demonstrated that only the fastest quench rates (≳500°C/s) result in the formation of a″ phase, and these materials exhibit a reversible thermally-induced β-a″ transformation at low temperatures. In contrast, slightly slower water quench procedures lead to a β+ω microstructure, and these samples do not exhibit a thermally-induced β-a″ transformation, even when cooled to -168°C. Despite this, room temperature mechanical testing results indicate that a″ can be induced by stresses as low as 200 MPa. To explain these results, it is proposed that quenching stresses play a role in the competition between a″ and athermal ω phases at rapid quench rates. The present results are then reconciled with the body of literature and a broader understanding of phase stability in metastable β-titanium alloys
The Alliance-Outcome Relationship in Individual Psychosocial Treatment for Schizophrenia and Early Psychosis:A Meta-Analysis
No full textThe therapeutic alliance, or client-provider relationship, has been associated with better treatment engagement and outcomes for persons with schizophrenia-spectrum disorders (SSDs) and early psychosis in some studies, but not others. We conducted a meta-analysis of the research on alliance in SSDs and early psychosis across a range of interventions and outcomes. Parallel literature searches were conducted in PubMed and PsycINFO databases for articles between inception and 6/11/2020. English-language studies were included if they evaluated the relationship between alliance and a prospective outcome (treatment engagement, medication adherence, functioning, or total, positive, negative, or depressive symptoms) in an individual clinical treatment for SSDs/early psychosis and contained analyzable data. Correlations and partial correlations were meta-analyzed with random effects models to calculate mean across-study correlations and to carry out subsequent homogeneity and moderator variable analyses. Fourteen studies consisting of 2,968 participants that assessed six outcomes across six psychosocial treatments were included. Results indicated that better client-rated (r=.20) and other-rated (i.e., provider- or observer-rated; r=.25) alliance were associated with better treatment engagement. Treatment type and sample race/ethnicity, but not age, gender, or timing of alliance rating moderated the association between other-rated alliance and engagement. Further, better other-rated alliance was related to improvements in positive (r=-.14) and negative (r=-.22) symptoms. A strong therapeutic alliance is important for both engaging clients with SSDs and early psychosis in treatment and facilitating improvements in positive and negative symptoms. Delivery and monitoring of treatments for this population should include assessment of the therapeutic alliance from multiple perspectives
Post-pandemic Patient Safety Culture: A Case from a large Metropolitan Hospital Group in Taiwan
No full textPatient safety is the core goal of medical institutions. The present study focuses on the patient safety culture and staff well-being admit the COVID-19 pandemic. 337 employees in a large metropolitan hospital group who had participated in the quality improvement interventions completed an anonymous questionnaire of patient safety culture and personal well-being. The multiple regression analyses indicated that managerial role, seniority, female gender and direct contact with patient were significantly related to the positive attitude on overall or certain di-mensions of safety culture. Multivariate analysis also found that dimensions of teamwork cli-mate, safety climate, job satisfaction, and stress recognition as patient safety culture predicted staff exhaustion. Finally, comparing with the available institutional historic data in 2018, the COVID group scored higher on the working condition dimension of patient safety culture, but lower on the stress recognition dimension. The COVID group also scored higher on exhaustion. In the post-pandemic era, there seems to be an improvement on certain aspect of the patient safety culture among hospital staff, and the improvement is more prevalent for managers. However, exhaustion is also a poignant problem for all employees. These findings can inform hospital decision-makers in planning and implementing future improvements of patient safety culture and promoting employee well-being and resilience. Our findings also reveal directions for future research
“Why is it so different now I’m bisexual?”:young bisexual people’s experiences of identity, belonging, self-injury, and COVID19
No full textBisexual people demonstrate higher rates of Non-Suicidal Self-Injury (NSSI) in comparison to other groups. This study aimed to explore bisexual people’s experiences of sexuality, NSSI and the COVID19 pandemic. Fifteen bisexual people (16-25 years old) with experience of NSSI participated in online qualitative interviews. Thematic analysis was used. Preliminary findings were shared with a subset of participants for member-checking. Participants described experiences of falling between the binary worlds of heterosexuality and homosexuality and described discrimination and invalidation related to this. Lack of access to positive bisexual representation contributed to feelings of self-loathing, with NSSI used to manage emotions or self-punish. The effect of lockdown was not clear cut, depending on personal circumstances and meanings of social interaction for participants. There is a need for greater recognition of significant societal narratives around bisexuality within clinical formulations of mental health difficulties and NSSI within this population
Electrostatic Perturbations from the Protein Affect C-H Bond Strengths of the Substrate and Enable Negative Catalysis in the TmpA Biosynthesis Enzyme
No full textThe nonheme iron dioxygenase 2-(trimethylammonio)- ethylphosphonate dioxygenase (TmpA) is an enzyme involved in the regio- and chemoselective hydroxylation at the C1-position of the substrate as part of the biosynthesis of glycine betaine in bacteria and carnitine in humans. To understand how the enzyme avoids breaking the weak C2-H bond in favor of C1-hydroxylation, we set up a cluster model of 242 atoms representing the first and secondcoordination sphere of the metal center and substrate binding pocket and investigated possible reaction mechanisms of substrate activation by an iron(IV)-oxo species by density functional theory methods. In agreement with experimental product distributions, the calculations predict a favorable C1-hydroxylation pathway. The calculations show that the selectivity is guided through electrostatic perturbations inside the protein from charged residues, external electric fields and electric dipole moments. In particular, charged residues influence and perturb the homolytic bond strength of the C1-H and C2-H bonds of the substrate, and strongly strengthens the C2-H bond in the substrate-bound orientation
Distributed Ledger Technologies to Foster Energy Transition in Smart Cities: Peer-to-Peer Electricity Trading Case
No full textTowards A Peace with Global Justice? The Struggle within the International Peace Architecture
No full textThe growing connection between peace and justice depends upon a long history of expanded rights claims emanating from critical agency and global subalterns. Their political scripts have partly driven the development of the international peace architecture (IPA), a series of layers, sediments, and theories built up through international and local scale peace praxis over the last century. It has often required an alliance with powerful actors and an international consensus. Its evolution challenges the Western framed approach to peacemaking from various directions- regional, methodological, theoretical, and ethical. The logical scientific conclusion of this process appears to equate peace with post-colonial versions of global justice and sustainability, drawing on subaltern perspectives and epistemological advances. However, blockages, counter-peace dynamics, including spoiling and authoritarian outcomes in many peace processes across the world, tend to underline the limited pragmatic traction of the peace-justice nexu